Field of the Invention and Related Art Statement
This invention relates to an endoscope apparatus wherein an attachment such as a hood fitted to the tip of the endoscope can be prevented from falling off.
Recently, endoscopes have come to be extensively used in the medical field and industrial field.
There is a prior art example in which the above mentioned endoscopes can be fitted with an optical adapter 3 which can change the visual field direction in the tip (formation) part 2 of the endoscope bodY 1 as shown in FIG. 1 so that a proper observation in response to an object may be made.
The above mentioned endoscope 1 is provided with an illuminating optical system by a light guide 4 transmitting an illuminating light and emitting it from the tip surface, an objective optical system 5 and an observing optical system having the entrance end surface of an image guide 6 as an image transmitting means arranged in the image forming position of this objective optical system 5.
The above mentioned tip part 2 is provided on the outer peripheral surface with a screw part 7 so that a side viewing optical adapter 3 may be in order that a side view may be observed. This optical adapter 3 is fitted with a prism 9 provided with a reflecting surface 8.
In case the above mentioned optical adapter 3 is not fitted, a hood will be fitted.
Also, the endoscope body 1 may be fitted in the tip part 2 with a gourd-shaped centering device 11 as shown in FIG. 2 so that the observing position may be set near the center axis of a pipe or the like and it may be easy to observe the inner peripheral surface of the pipe. In case the centering device 11 is not fitted, a hood will be fitted.
Known as a means of preventing the above mentioned removably fitted member from dropping is a Japanese Utility Model Application Laid Open No. 87704/1982.
This relates to an optical adapter or hood having windows coinciding respectively with an observing optical system and illuminating optical system within an endoscope body. This optical adapter or hood requires a positioning means for the endoscope body and is complicated in the structure.
On the other hand, there is also an endoscope to which is connected a substantially hollow cylindrical hood of a non-conductive material for electric insulation or a substantially hollow cylindrical hood 12 prerequisited to be removed to be repaired as is described in a Japanese Patent Application No. 26512/1987 (See FIG. 3a).
Such a hood is bonded and fixed to the endoscope body but has a danger that, when it is exposed to a high temperature by mistake during inspection, the bonding strength is reduced by the variation with the lapse of time and a vibration or shock is applied to the tip part of the endoscope, the connection will loosen and the hood will fall off.
The endoscope connected with such a substantially hollow cylindrical member has so far no means of warning the inspector in advance of the loosening of the connection.
That is to say, as shown in FIG. 3b, even when the screwed engagement of the female screw part 14 of the substantially hollow cylindrical member 13 of a hood or the like with the male screw part 7 of the endoscope body 1 is released, the observing visual field of a view angle .beta. will not be disturbed by the substantially hollow cylindrical member 13.
In the means shown in the Japanese Utility Model Application Laid Open No. 87704/1982, as a window requiring positioning for the observing optical system and illuminating optical system is formed, there are defects that the structure is complicated and a work of a high precision is required.
Also, in the endoscope in which the substantially hollow cylindrical member is connected to the tip part, as the observing visual field of the endoscope will not be disturbed even at the time when the substantially hollow cylindrical member is separated from the endoscope body as shown in FIG. 3b, even if the connection of the substantially hollow cylindrical member loosens during the endoscope inspection, the inspector will not be able to recognize it. If the inspection is continued as it is, the substantially hollow cylindrical member will drop and a serious accident will follow. Thus, there have been defects that essentially unnecessary disassembling and recovering operations will be necessary and a time loss and high cost will be caused.
An endoscope provided with a removable inserting guide is disclosed in U.S. Pat. No. 4,676,230.
This prior art example is so made that the inserting guide may not drop from the tip of the insertion part. This structure is comparatively simple but is considerably more complicated than the above described devices in FIGS. 1 to 3.